The field of the present invention is pumps and actuators for pumps having air driven diaphragms.
Pumps having double diaphragms driven by compressed air directed through an actuator valve are well known. Reference is made to U.S. Pat. Nos. 5,213,485; 5,169,296; and 4,247,264; and to U.S. Pat. Nos. Des. 294,946; 294,947; and 275,858. An actuator valve using a feedback control system is disclosed in U.S. Pat. No. 4,549,467. The disclosures of the foregoing patents are incorporated herein by reference.
Common to the aforementioned patents on air driven diaphragm pumps is the presence of an actuator housing having air chambers facing outwardly to cooperate with pump diaphragms. Outwardly of the pump diaphragms are pump chamber housings with inlet manifolds and outlet manifolds. Ball check valves are also positioned in both the inlet passageways and the outlet passageways. The actuator between the air chambers includes a shaft running therethrough which is coupled with the diaphragms. An air valve controls flow to alternate pressure and exhaust to and from each of the air chambers so as to result in reciprocation of the pump. The air valve is controlled by a pilot system controlled in turn by the position of the pump diaphragms. Thus, a feedback control mechanism is provided to convert a constant air pressure into a reciprocating distribution of pressurized air to each air chamber. A vast range of materials are able to be pumped safely and efficiently using such systems.
Air driven systems, using the expansion of compressed gasses to convert potential energy into work, can experience problems of icing when there is moisture in the compressed gas. As the gas expands, it cools and is unable to retain as much moisture. The moisture condensing from the cooled gas can collect in the passageways and ultimately form ice. This can result in less efficient operation and stalling.